Merge branch 'sh-fix-time-zones' into 'master'

Fix time zone config not respected in multi-threaded servers

Closes #233259

See merge request gitlab-org/gitlab!39778

changelogs/unreleased/sh-fix-time-zones.yml

+---
+title: Fix time zone config not respected in multi-threaded servers
+merge_request: 39778
+author:
+type: fixed

config/initializers/time_zone.rb

 Time.zone = Gitlab.config.gitlab.time_zone || Time.zone
+# The default is normally set by Rails in the
+# active_support.initialize_time_zone Railtie, but we need to set it
+# here because the config settings aren't available until after that
+# runs. We set the default to ensure multi-threaded servers have the
+# right value.
+Time.zone_default = Time.zone
+Rails.application.config.time_zone = Time.zone